Electric distribution grids (including microgrids) are typically operated with a number of constraints that allow delivery of power at a certain quality and reliability level. A goal associated with operating a power distribution network, for example, is establishing acceptable voltage conditions for all customers while delivering power as efficiently as possible. In many power distribution networks, the voltage profile along the distribution feeder and the flow of reactive power (also known as VARs) on the feeder are typically maintained by a combination of voltage regulators and switched capacitor banks installed at various locations on the feeder and in its associated substation.
Large distribution systems may include microgrids and non-microgrid branches. A microgrid typically includes localized groupings of loads, generation sources, and storage devices that are connected to a traditional centralized grid, or macrogrid. Optimizing an entire feeder network, including microgrids, and coordinating voltage and volt-amps-reactive (VAR) control can be a formidable task, particularly when network conditions change. Traditionally, feeder voltage regulators and switched capacitor banks are operated as independent devices, with no direct coordination between the individual controllers. Such an approach can be effective for maintaining acceptable voltage and reactive power flow near the controllers, but typically does not produce optimal results for the entire feeder.